Rice, Henry J.

Abstract [en]

On-going research and development by the European aeronautical community towards the reduction of civil aircraft noise has been investigating the shielding of engine noise sources by airframe components (wing/fuselage/empennage). In order to assess the noise reduction benefits attainable from such novel configurations, it is necessary to develop appropriate acoustic evaluation tools. In this paper, the Tam-Auriault jet noise model, with a RANS solution input, in conjunction with a Fresnel-Kirchhoff diffraction method is used to make isolated and shielded far-field jet noise predictions. This methodology is employed as a sensitivity analysis tool in order to establish the relative importance of the source location, spatial extent and directivity in jet noise shielding predictions.

Although, the predicted isolated jet directivity agrees well with far-field empirical values, the predicted levels of shielding are much larger than those observed in the available data. A preliminary investigation into the possible causes of this discrepancy indicates that the introduction of the shield adjacent to the jet may result in the generation of new ‘installation sources’, which limit the shielding achievable in practical applications.